Monday, September 14, 2009
THE number of sunspots has declined dramatically in the past two years – but scientists say it is too early to tell if it is the start of a solar depression that could lead to cooler weather on Earth.
Over the past millennium, whenever the sun has had long periods of low sunspot numbers, Earth has weathered equally long cold snaps. The most famous of these was the Maunder Minimum of 1645 to 1715, when sunspots all but vanished for 70 years. It coincided with the coldest period of the Little Ice Age.
For the past two years, sunspots – dark and intensely magnetic blotches on the sun’s surface – have been at their fewest since 1913.
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”This is the quietest sun we’ve seen in almost a century,” said NASA solar forecaster David Hathaway. ”Since the space age began in the 1950s, solar activity has been generally high … We’re just not used to this type of deep calm.”
Sunspots cause other solar activity such as solar flares and coronal mass ejections, radiation from which can interfere with Earth’s magnetic field, upper atmosphere and, many scientists believe, climate.
Scientists expect to record 290 spotless days this year. Last year, there were 266, the most spotless days since 1913, when there were 311 recorded.
This article was posted: Monday, September 14, 2009 at 4:36 am